How to Make It
In a large enameled cast-iron casserole, combine the pork, beef broth, water, celery, carrot and olive oil and bring to a simmer. Cook over moderately low heat, skimming occasionally, until the meat is tender, about 1 hour.
Using a slotted spoon, transfer the meat and vegetables to a bowl. Add the leeks to the casserole and bring to a boil, then simmer over moderately low heat, stirring occasionally, until softened, about 20 minutes. Ladle 2 cups of the hot broth into a glass measuring cup.
In a medium bowl, whisk the egg yolks with the whole egg, then whisk in the lemon juice. In a small bowl, whisk the cold water with the flour, then whisk it into the egg mixture. Gradually add the reserved 2 cups of hot broth to the egg mixture, whisking constantly. Add this mixture to the casserole and simmer over moderate heat, stirring, until the sauce thickens, 2 to 3 minutes. Return the meat and vegetables to the casserole and reheat. Stir in the dill and serve.